Simrad IS40 Operator's Manual page 25

Auto - Calibration via reference to GPS SOG value
This is an AutoCal facility that uses speed over ground (SOG) from your GPS and compares the
average of SOG against the average boat speed from the speed sensor for the duration of the
calibration run.
¼ Note:
This calibration should be made in calm sea with no effect from wind or tidal current.
1. Bring the boat up to cruising speed (above 5 knots)
2. Select Auto on the Boat speed calibration page
3. When the calibration is completed the Boat speed calibration scale will show the adjusted
percentage value of the boat speed.
Use SOG as boat speed
If boat speed is not available from a paddle wheel sensor, it is possible to use speed
over ground from a GPS. SOG will be displayed as boat speed and used in the true wind
calculations and the speed log.
Manual adjustment of boat speed
Adjust the boat speed manually by selecting the Boat speed percentage slider. Adjust the
percentage up or down as desired. Confirm the value. Select OK once complete.
Distance Reference
This facility enables the user to calibrate the log accurately and simply. Calculations are
performed by the display that works out the boat speed over a known distance.
To calibrate the boat speed via a distance reference you will need to complete consecutive
Setup | IS40 Operator Manual
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